ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-5 of 19 Abstracts search results

Document: 

SP75-05

Date: 

September 1, 1982

Author(s):

F. Wayne Klcriber and Dcrh-Yinn lee

Publication:

Symposium Papers

Volume:

75

Abstract:

Rigid pavement design procedures currently in use con-sider only the modulus of rupture strength of concrete in deter-mining the fatigue life of concrete highway pavements. The effects of entrained air, water-cement ratio, and aggregate type are considered only to the extent they affect the modulus of rup-ture of the concrete. The purpose of this study was to determine the effects of air content, water-cement ratio, and aggregate types on the flexural fatigue strength of plain concrete and to develop fatigue curves that incorporate these effects and thus could be used for design. Fifteen series of concrete were investigated in this study. The variables consisted of air content, water-cement ratio, coarse aggregate type and fine aggregate type. Over 350 beams were sub-jected to flexural one-third point fatigue loading in which the bottom fiber stress varied from essentially zero to a predeter-mined maximum stress. Of the variables investigated, air content and coarse aggregate type were determined to have the greatest effect on flexural fatigue strength. Water-cement ratio also affects the fatigue strength but to a lesser degree. Fatigue strength of concrete was not significantly influenced by the type of fine aggregate used.

DOI:

10.14359/6403


Document: 

SP75-03

Date: 

September 1, 1982

Author(s):

Stuart E. Swartz, Chen-Ming James Huang, and Kuo-Kuang Hu

Publication:

Symposium Papers

Volume:

75

Abstract:

As part of an ongoing experimental/analytical research effort to evaluate the feasibility of a test method for fracture toughness of concrete, forty-eight plain concrete beams have been tested in bending to failure. All beams were notched and then precracked to different crack length/depth ratios-prior to load-ing to failure. The precracking was done using an electro-hydrodynamic materials testing system and displacement control. The beams which were cracked in fatigue were subjected to one million cycles of sinusoidal loading at 4 Hz. After the cycling was complete on a beam, the crack depth was determined using a compliance calibration technique following which the beam was loaded to failure. A load versus crack-mouth-opening-displacement trace was plotted during this final load run. For each beam tested in fatigue, a companion beam was pre-cracked "statically" by loading in repeated cycles until the crack depth, as measured by compliance calibration, matched that of the fatigued specimen. The studies were made on two different beam sizes in three and four-point bending with two different mix designs. Test results indicate the failure strength and associated maximum stress-intensity of the statically precracked beams to be slightly higher than those precracked in fatigue.

DOI:

10.14359/6401


Document: 

SP75-04

Date: 

September 1, 1982

Author(s):

Jan Ove Holmen

Publication:

Symposium Papers

Volume:

75

Abstract:

In this investigation, the effect of various load histories on the fatigue behaviour of plain concrete was studied. (1). A total of 462 cylindrical specimens (100x250 mm) were tested statically and dynamically in compression. In addition, a total of 18 cylinders (150x300 mm) plus 132 cubes (100 mm) were tested statically. In addition to fatigue strength, special interest has been paid to the deformation characteristics of the concrete. A total of 140 specimens were tested under constant amplitude loading. Based on the fatigue strength results, empirical ex-pressions between the stress level (S), number of cycles (N) and probability of failure (P), S-N-P relationships, were derived. Using deformation characteristic results, an empirical expression for the total longitudinal strain (&maX) as a function of the cycle ratio (N/NF) and the loading time (t) was derived. This expression can be used to predict the fatigue life from deforma-tions early in the life. A total of 180 specimens were tested under various variable load histories of a given statistical distribution. The effect of both small and large amplitudes on fatigue strength and deforma-tion characteristics was examined. Based on fatigue strength results, the validity and limitations of the Palmgren-Miner hypothesis were examined. The PM hypothe-sis was found to give more or less unsafe predictions of the fatigue life depending on the load histories. Features of the loading histories affecting the accuracy of the hypothesis are discussed and an empirical relationship between loading histogram parameters and the Miner-sum at failure is presented. The empirical expression for the total longitudinal strain de-rived for constant amplitude tests is modified for tests under variable load histories.

DOI:

10.14359/6402


Document: 

SP75-02

Date: 

September 1, 1982

Author(s):

A. E. Naaman

Publication:

Symposium Papers

Volume:

75

Abstract:

ified. Experimental data on the fatigue life of prestressing strands are compared with data on the fatigue life of partially prestressed beams. A close correlation results of a reliability based models of partially prestressed beams in which serviceability and ultimate strength limit states is observed. Global were considered, are presented. They strongly suggest that fatigue in the reinforcement is a controlling limit state that must be seriously accounted for in design.

DOI:

10.14359/6400


Document: 

SP75-15

Date: 

September 1, 1982

Author(s):

H. Roper and G. B. Hetherington

Publication:

Symposium Papers

Volume:

75

Abstract:

Fifty concrete beams reinforced with 24 mm deformed bars in the tension zone, were subjected to sinusoidal load fluctuations at 6.7 Hz in air, 3 percent sodium chloride solution and natural sea water. Total numbers of cycles at failure varied between 10' and lo7 for calculated stress ranges in the steel between 100 MPa and 280 MPa. Two types of tension reinforcement were compared; one was a hot-rolled 230 Grade deformed bar, and the second a cold.-worked 410 MPa Grade deformed similar chemical composition. bar with a As practised in some countries, cold-working by twisting was found to reduce the fatigue endurance of the deformed reinforcement in concrete beams tested both in air and sea water. The detrimental effect of sea water or sodium chloride solution gaining access, via concrete cracks, to bars subjected to fatigue loading was confirmed. In sea water the influence of cyclic loading on the hot-rolled series was different to that on the cold-worked series; for the latter series a decrease in slope of portion of the S-N curve was observed, which may represent a fatigue limit within lo7 cycles, whereas for the former no such change in slope exists. A reduction of fatigue endurance was observed for tests in a 3 percent sodium chloride solution compared with data for beams loaded in natural sea water. when A fractographic investigation was conducted on typical failure surfaces of bars subjected to tests in concrete,in air, and in sea water.

DOI:

10.14359/6413


1234

Results Per Page